The present invention relates to a method and a device for the surface machining of workpieces composed of non-brittle materials in optical lens manufacturing, and to a tool for this purpose. The invention relates in particular to the industrial machining of prescription surfaces of spectacle lenses composed of plastics such as polycarbonate, CR39 and so-called “high index” materials.
This machining is usually performed on an injection molded plastic spectacle lens “blank”, which has a standardised, finished convex outer surface with, for example, a spherical or progressive shape. Machining gives the generally concave inner or prescription surfaces a spherical, aspherical, toroidal, atoroidal, progressive or freeform geometry, depending on the desired optical effect. After blocking the spectacle lens blank with its outer surface on a blocking piece, the typical, conventional sequence in machining of the inner surface provides for a milling or rotational machining process for producing the optically active shape, followed by a fining or polishing process in order to obtain the necessary surface quality.